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Biology Year 13 > Neuronal Communication✅ > Flashcards

Neuronal Communication✅ Flashcards

1
Q

What pathway does a nervous response usually follow

A

Sensory receptor
Sensory neurone
Relay neurone
Motor neurone
Effector

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2
Q

What is the function of a sensory neurone

A

Transmits impulses from receptors to relay neurones in the central nervous system

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3
Q

What are the key structural features of a sensory neurone

A

One dendron (carrying impulse from receptor to cell body)

One axon (carrying impulse from cell body to a relay neurone)

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4
Q

What is the function of a relay neurone

A

Transmit impulses between neurones

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5
Q

What are the key structural features of a relay neurone

A

Many clusters of dendrites, each leading to a dendron.

Each dendron passes to central cell body

Short axon carries impulses from the cell body to many synaptic endings

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6
Q

What is the function of a motor neurone

A

Transmit impulses from a relay neurone to an effector (ie muscle or gland)

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7
Q

What are the key structural features of a motor neurone

A

Dendrites leading to the cell body. One long axon (carrying impulses from cell body to effector)

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8
Q

How do sensory and motor neurones look different

A

Sensory: cell body and nucleus in middle of dendron

Motor: cell body and nucleus left of dendron

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9
Q

What does a dendron, axon, dendrites, myelin sheath, nodes of ranvier, cell body and nucleus look like on a diagram of a neurone

A

Dendron: the start of the axon

Nucleus: small circle in cell body

Cell body: surrounds nucleus

Dendrites: little circles on end of

Myelin sheath: around the axon

Node of ranvier: gaps in myelin sheath

Axon: line connecting cell body away

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10
Q

What are myelin sheaths made from, what do they do

A

Fat produced by Schwann cells

Speed up nervous impulse by enabling saltatory conduction (axon membrane can depolarize only at nodes of ranvier, action potential jumps between nodes which is more efficient then entire membrane being depolarized

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11
Q

What do receptors do

A

Detect change in environment and convert stimulus into electrical impulse

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12
Q

What are the 5 types of stimulus

A

Pressure
Light
Chemicals
Temperature
Sound

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13
Q

What receptor and describe mechanistic detail for pressure stimulus

A

Receptor: pacinian corpuscle

Detail: pressure applied to skin opens stretch-mediated sodium ion channels, triggering an action potential

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14
Q

What receptor and describe mechanistic detail for light stimulus

A

Receptor: rods cells (in retina of eye)

Detail: light causes a chemical reaction to occur in rod cells (ie breakdown of rhodopsin), which alters the permeability of the cell membrane to sodium ions

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15
Q

What receptors and describe mechanistic detail for chemical stimulus

A

Receptors: taste receptor, olfactory cells

Detail: molecules or ions (eg salt, sugar, odour molecules) bind to receptors on the receptor cell membranes, this causes a second messenger response, cAMP levels rise and alter permeability of the cell membranes to Na+ ions. Depolarization occurs and triggers an action potential

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16
Q

What receptor and describe mechanistic detail for temperature stimulus

A

Receptor: thermoreceptors

Detail: specialized sensory neurones. The permeability of their membranes to Na+ ions changes with temperature

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17
Q

What receptor and describe mechanistic detail for sound stimulus

A

Receptor: hair cells (in the ear)

Detail: sound waves move cilia on hair cells, which triggers changes in membrane permeability to K+ ions

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18
Q

What is action potential

A

The change in potential difference across a neurone membrane following a stimulus (approx +40mV)

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19
Q

What is the resting potential in mV

A

-70mV

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20
Q

How does the sodium-potassium pump produce resting potential

A

3 Na+ ions pumped out of neurone (by active transport) for every 2 K+ ions pumped in. This sets up an imbalance of positive charge (ie outside the neurone is more positive then inside)

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21
Q

How do K+ channels produce resting potential

A

Some K+ channels remain open, this enables some K+ ions to diffuse out of neurone, down a concentration gradient. Even more positive charge therefore builds up outside of the neurone

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22
Q

What happens during an action potential

A

Resting potential

Na+ channels open. Na+ ions diffuse into neurone down an electrochemical gradient

Initial influx on Na+ ions causes more voltage gated Na+ channels to open (depolarization)

Na+ ions continue to diffuse into neurone through voltage gated Na+ channels until potential difference reaches +40mV. Voltage-gated Na+ channels then close and voltage-gated K+ channels open

K+ ions diffuse out of neurone, reducing the positive charge inside the neurone and repolarising the membrane

Voltage-gated K+ channels close. The membrane becomes hyper polarized (due to K+ ions leaving, inside becomes more negative then resting state). Known as refractory period- no more action potential occurs until resting potential restored. Na-K pumps return the neurone to resting potential

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23
Q

The propagation of an action potential involves what events

A

Na ions enter a neurone and depolarize it

Na ions diffuse further along the neurone

The increased positive charge caused by diffusion of Na ions open more voltage-gated sodium ion channels

Action potential passes along the neurone

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24
Q

What 3 factors affect the speed of nerve impulses

A

Greater axon diameter (reduced resistance to ion flow)

Higher temperature

Presence of myelin

25
Q

Describe the transmission across a synapse

A

Action potential passes to end of presynaptic neurone (presynaptic knob)

Voltage-gated Ca2+ ion channels open

Ca2+ ion influx causes vesicles containing neurotransmitters (acetylcholine) to fuse with neurones cell membrane

Neurotransmitters (acetylcholine) released into synaptic cleft by exocytosis

Neurotransmitters (acetylcholine) diffuse across synaptic cleft and bind to receptors on postsynaptic neurones cell membrane

Na ion channels and triggered to open, causing depolarization and an action potential in postsyanptic neurone (if sufficient neurotransmitters bind and threshold value surpassed)

26
Q

What are the roles of synapses

A

Ensure impulses travel in only 1 direction

1 presynaptic neurone can signal to many postsynaptic neurones, this enables signals to be passed to different effectors

Enable 1 sensory neurone to revive signals from several receptors, this provides information about extent of stimulus. Spatial summatation occurs- ie sometimes an action potential in a postsyanptic neurone will occur only if several presynaptic neurones release neurotransmitters

Enable temporal summation- ie sometimes a postsynaptic action potential occurs only when several impulses have travelled down a presynaptic neurone. Each impulse releases more neurotransmitters until threshold depolarization is surpassed in postsynaptic neurone

27
Q

What is the central nervous system (what types of neurones)

A

Brain and spinal cord
Relay neurones

28
Q

What is the peripheral nervous system (what type of neurones)

A

Everything other then brain and spinal chord
Sensory and motor neurones

29
Q

What is the somatic nervous system

A

Conscious control input from sense organs output to skeletal muscles

30
Q

What is the autonomic nervous system

A

Subconscious control input from internal receptors output to smooth muscles and glands

31
Q

What is the sympathetic and parasympathetic motor systems

A

Sympathetic: fight or flight responses, neurotransmitters-noradrenaline

Parasympathetic: relaxing responses, neurotransmitter-acetylcholine

32
Q

What is the function of the cerebrum where is it located

A

Coordinates voluntary responses
Top of the brain (a bit right)

33
Q

What is the function of the cerebellum where is it located

A

Controls balance and posture
Weird looking tree bit bottom right of brain

34
Q

What is the function of the medulla oblongata, where is it located

A

Autonomic functions (eg heart rate, breathing rate)
Bottom of brain (just left of spinal chord)

35
Q

What is the function of the hypothalamus, where is it located

A

Autonomic functions (eg thermoregulation)
At the top of the medulla oblongata

36
Q

What is the function of the pituitary gland where is it located

A

Release hormones that control other glands in the body
Left of hypothalamus

37
Q

Describe the stimulus, receptor, location of relay neurone, effector and importance of the knee-jerk reflex

A

Stimulus: firm tap below kneecap
Receptor: stretch receptor in muscles
Location: spinal chord
Effector: muscles in upper leg
Importance: maintaining balance

38
Q

Describe the stimulus, receptor, location of relay neurone, effector and importance for the blinking reflex

A

Stimulus: touch on cornea
Receptor: touch receptor in the cornea
Location: lower brain stem
Effector: muscles in eyelids
Importance: preventing damage to the eyes

39
Q

Describe skeletal muscle

A

Appearance:Striated

Location:Attached to bones via tendons

Type of contraction:Voluntary (conscious), fast, short in duration

40
Q

Describe cardiac muscle

A

Appearance: striated (fainter striations then skeletal)

Location: heart

Type of contraction: involuntary, intermediate speed, intermediate duration

41
Q

Describe smooth muscle

A

Appearance: non-striated

Location: walls of blood vessels, digestive system, excretory system

Type of contraction: involuntary, slow, can be long-lasting

42
Q

describe the role of cell signalling in the nervous system (2 marks)

A

transmits nervous impulses between neurones

across synapses/ synaptic clefts

for coordinated responses to stimuli

idea of summation

43
Q

explain why homeostasis relies on cell signalling (2 marks)

A

receptor cells need to communicate with controller/coordinator/brain

controller/coordinator/brain needs to communicate with effectors

idea of several cell types/tissues/systems involved in responses

44
Q

state the 2 structural differences between a sensory neurone and a motor neurone (2 marks)

A

position of cell body (described)

sensory neurones has one (long) dendron

motor neurones has many dendrites leading to its cell body

45
Q

many relay neurones are not surrounded by myelin sheath, suggest why (2 marks)

A

relay neurones tend to be short

the increased rate of conduction in the presence of myelin sheath would make little difference

46
Q

explain why sensory receptors are considered to be transducers (1 mark)

A

they convert one form of energy to another form of energy

47
Q

state the form of energy converted to electrical impulses by
A: rod cells
B: thermoreceptors
C: Pacinian corpuscles
D: olfactory cells

A

A: light
B: heat/thermal
C: mechanical pressure
D: chemical

48
Q

describe how the transmission of nerve impulses differs between myelinated and unmyelinated neurones (3 marks)

A

(with myelination)
faster impulses

saltatory conduction

longer local circuits

nodes of Ranvier present

49
Q

explain why a neurone will not produce action potentials that vary in magnitude (3 marks)

A

all or nothing principle

threshold potential must be surpassed

no action potential will occur if Na+ ion influx is insufficient

stimulus strength does not affect action potential magnitude (above threshold)

K+ ion channels always open at the same point in an action potential (which results in the potential difference never surpassing a particular value)

50
Q

describe how acetylcholine is released from a presynaptic neurone (3 marks)

A

calcium ion channels open/ calcium ions diffuse into presynaptic neurone

vesicles fuse with the presynaptic membrane

acetylcholine is released by exocytosis

51
Q

use the concept of temporal summation to explain why a weak stimulus may be filtered out and not produce a response from the nervous system (3 marks)

A

a weak stimulus produces less frequent action potentials

fewer neurotransmitter molecules are released

less depolarisation (in post synaptic neurone)

threshold is not reached

no postsynaptic action potential

52
Q

suggest why it is important for neurotransmitters such as acetylcholine to be recycled (2 marks)

A

to be released again from the presynaptic neurone

regulates the concentration of neurotransmitter in the synaptic cleft

prevents re-binding to receptors when signalling has stopped

53
Q

which specific branch of the peripheral nervous system would produce the following responses
A: a person gripping a cup with their hand
B: an increase in sweat production
C: constriction of pupils (3 marks)

A

A: somatic
B: sympathetic
C: parasympathetic

54
Q

explain why a person struggling to move normally may have suffered damage to either their cerebrum or cerebellum (2 marks)

A

the cerebrum controls voluntary movements

cerebellum coordinates balance and non-voluntary movements

55
Q

state the location of the relay neurones in
A: knee-jerk reflex
B: the blinking reflex (2 marks)

A

A: spinal chord
B: brain stem

56
Q

describe and explain the general characteristics of reflex responses that aid the survival of organisms (4 marks)

A

few synapses

short pathway

a dangerous stimulus is responded to quickly

innate/ no learning required

the response is stereotyped/consistent/always the same

involuntary

prevents overloading of the brain

57
Q

explain how the typical neural pathway of a reflex maximises its effectiveness (3 marks)

A

2 synapses

short relay neurone

sensory neurone does not need to travel deep into the brain

responses is quicker

58
Q

how will the length of the following sarcomere features change during muscle contraction (5 marks)

A: A band
B: I band
C: myosin filaments
D: actin filaments
E: H zone

A

A: no change
B: shortens
C: no change
D: no change
E: shortens

59
Q

outline the role of calcium ions in muscle contraction (3 marks)

A

calcium ions bind to troponin

changes the shape of troponin

displaces tropomyosin

uncovers myosin binding sites on actin

enables myosin heads to bind to actin

Biology Year 13 (6 decks)

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